1. Field of the Invention
The present invention relates to a technique of, so-called, steer-by-wire type steering apparatus and method for an automotive vehicle in which a clutch to link an steering input section to steered road wheels which are mechanically separated is interposed in a midway through a steering system from the steering input section to the steered road wheels.
2. Description of the Related Art
A Japanese Patent Application First Publication No. 2002-145098 published on May 22, 2002 (which corresponds to a U.S. Pat. No. 6,442,462 issued on Apr. 27, 2002) exemplifies a previously proposed steering system of the steer-by-wire type. In the previously proposed steering system disclosed in the above-described Japanese Patent Application First Publication, a torque sensor is interposed between a steering wheel and a reaction motor. In a case where part of a system fails, the clutch is connected so that a steering force with a vehicle driver directly turns (steers) tire (or road) wheels and a torque assistance control (power steering) by means of a controllable motor according to a signal of the torque sensor.